Our research has focussed on the feasibility of mapping genes through linkage disequilibrium. Linkage disequilibrium is manifested at the population level and thus has certain advantages over mapping genes by pedigree analysis. In particular, it is our hope that this strategy can be used to map genes whose phenotype depends, at least in part, on non- genetic factors such as exposure to viruses or toxins. In general, linkage disequilibrium will only exist between genes that are physically very close to each other, so we needed to identify types of populations that might show linkage disequilibrium between genes that are relatively loosely linked. Two types of populations that meet this requirement are (1) populations that have a recent bottleneck or founder event in their evolutionary history and (2) populations that have a recent history of racial admixture. The former type of population might be less general or useful on theoretical grounds; for instance, if there is a reduction in overall genetic variability. We have therefore concentrated on the evaluation of mapping genes in racially admixed populations. Our investigations thus far have been designed to identify and evaluate all of the relevant parameters expected to be encountered in a mapping study of this sort. Additionally, our work has focussed on identification and evaluation of the strategies or criteria used for discerning that linkage exists between a pair of genes.
